Projection display device
US5760875A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 8, 1997 |
| Grant date | Jun 2, 1998 |
| Priority date | — |
| Expiry date | Jan 8, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/3152
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A projection display device comprises: a diaphragm for the illuminating system disposed in the vicinity of a focal point of the light collected by the concave mirror; a collimation lens for rendering parallel the light passing through the aperture of the first diaphragm; a scattering-type liquid crystal light valve for forming forming image on its displaying surface; a field lens for converging the light rendered parallel by the collimation lens; a projection lens having an entrance pupil disposed in the vicinity of a focal point of the light converged by the field lens; and a second diaphragm having an aperture and provided in the projection lens. An aperture varying section of the first diaphragm varies the aperture diameter of the diaphragm of the illuminating system, and the other aperture varying section varies the aperture diameter of the diaphragm of the projection lens, thereby varying the diameter of an entrance pupil.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.